Attached is a solution.
Hope it helps.
ciao
m.
--
Matteo Sisti Sette
matteosistisette@gmail.com
http://www.matteosistisette.com
#N canvas 97 215 450 431 10;
#X obj 134 135 tgl 15 0 empty empty empty 17 7 0 10 -262144 -1 -1 0
1;
#N canvas 0 293 450 300 $0-subpatch 0;
#X text 114 152 this is a subpatch;
#X restore 355 93 pd $0-subpatch;
#X obj 78 214 list prepend $0;
#X msg 66 295 ; pd-$1-subpatch vis $2;
#X connect 0 0 2 0;
#X connect 2 0 3 0;
#X coords 0 -1 1 1 85 60 1 100 100;